almost too much of a fairy tale in 1995, as a mediocre college football player at the university of maryland, kevin decided that the cotton t-shirts he was wearing at practice were just too sweaty. what made you think -- who cares about a cotton t-shirt, that you sweat through? >> well, i was pretty short and slow, and so my incentive was giving me that little bit of an advantage. >> reporter: so, he made shirts with synthetic fabric that would wick away the sweat. he didn't invent the fabric. he just made the shirts. >> i'll make them up, send a few out, and i thought it was going to be easy. and the fact of the matter is, it doesn't work like that. >> reporter: he wracked up $40,000 in credit card debt in his grandmother's basement. and a ton of hard work. but i saw first hand, plank is a guy who seems to like hard work. maybe too much. >> all right, so, welcome to combine training. this is going to be -- it's going to hurt a little bit. >> reporter: great. all mill interviews hurt a little bit. this one will be worse. >> no question. not as much up here. >> reporter: he invited me to one